The present invention relates to an arrangement for controlled engagement of the tools of a mining machine, especially a coal planer, with a mine face, in which the mining machine is mounted on the front face of an abutment, for instance a scraper conveyor, for reciprocation along the mine face and which includes means for tilting the abutment and the mining machine mounted thereon about a substantially horizontal axis.
Such an arrangement is known in the art and disclosed in the German Auslegeschrift No. 23 19 910. This known arrangement includes a guide linkage comprising two parallel transversely spaced rods located above the sole of the mine gallery. The tilting unit for the abutment constituted by a scraper conveyor with a coal planer mounted for reciprocation on its front face, extends rearwardly of the scraper conveyor and includes a substantially vertically arranged fluid operated cylinder and piston unit, the cylinder of which is connected over fixed connecting elements to the rear face of the scraper conveyor, whereas the piston rod of the unit is connected to the guide rods rearwardly of a horizontal tilting axis by means of which the front ends of the guide rods are connected to the scraper conveyor. By impinging the piston of the cylinder and piston unit on one or the other face thereof with pressure fluid it is therefore possible to tilt the scraper conveyor and the coal planer guided thereon in such a manner that the tools of the coal planer are pressed into the sole of the mine gallery or move out of the same.
A disadvantage of this known arrangement is especially the position of the tilting unit. As mentioned before this tilting unit extends in vertical direction and is located in close vicinity of the scraper conveyor to reduce thereby the free space between the scraper conveyor and the mine roof support, which, especially during mining of coal seams of small heights, is considerably small. This condition is further aggravated by the considerable distance of the guide linkage above the mine floor of the mine gallery. Even if a more or less satisfactory free space should be available, then it is only obtainable with a mine roof support in which the free forwardly extending roof shield is of considerable length. This in turn will lead to an unsatisfactory introduction of the force for supporting the mine roof.
Another disadvantage of this known arrangement is that the tilting unit is directly subjected to the influence of the material transported by the scraper conveyor. Thereby, not only the cylinder and piston unit of the tilting arrangement, but also the conduits for feeding pressure fluid thereto, are subjected to increased wear resulting from the dust of the material transported by the scraper conveyor. Likewise, the necessary valves for the operation of the cylinder and piston unit are subjected to the detrimental influence of the material transported by the scraper conveyor which will evidently result in the increased necessary maintenance.